As is well known and as shown in FIG. 10, the conventional chamfering machine includes: a chamfering width maintaining roller 50 for maintaining the chamfering width constantly during a chamfering; a horizontally maintaining roller 51 for horizontally maintaining the glass plate so as for the glass plate not to drop during a chamfering; and two glass plate shape sensing rollers for changing the chamfering direction of a diamond wheel in accordance with the shape of the glass plate, these two rollers being disposed at the opposite sides of the chamfering width maintaining roller in a parallel form. (Korean Utility Model application 89-10143, 88-22093 and 90-11609).
If a chamfering is to be performed with the above described chamfering machine, first the thickness of the glass plate, the chamfering angle and the chamfering width have to be decided, and then, the glass plate to be chamfered has to be mounted on a rotary suction securing table. Then a chamfering wheel motor unit has to be adjusted to an inclined posture by turning a handle so as for the unit to be fit to the chamfering angle, and then, the angle and height of the horizontally maintaining roller have to be adjusted.
Then, as shown in FIG. 10, the heights of the chamfering width maintaining roller 50 and the horizontally maintaining roller 51 have to be adjusted so as for the roller 51 to support the lower face of the glass plate, and so as for a stopper 52 of the roller 50 to be engaged with the lower edge of the glass plate to be chamfered.
Here, care should be exercised so that the upper portion of the roller 50 should not touch the lower portion of the glass plate to be chamfered.
If the roller is adjusted to too high a position as the result of a careless adjustment, a state as shown in FIG. 11 occurs. Therefore, when a chamfering wheel 53 chamfers the glass plate 54, the upper portion of the roller 50 is also chamfered, thereby causing a fatal damage to the roller 50. On the other hand, if the roller 50 is adjusted too low, the stopper 52 of the roller 50 departs from the edge of the glass plate, with the result that either the glass plate is broken, of the chamfering width is formed to narrow, thereby committing a faulty chamfering.
Thus a great importance lies in the adjustment of the glass plate shape sensing roller and in maintaining the chamfering width. However, the adjustments are very difficult to perform in the case of a glass plate.
For example, as shown in FIG. 9B, if a chamfering face width L of 15 mm and a chamfering angle of 8.degree. are to be attained in chamfering a glass plate 54 having a thickness of 5 mm, the height T of the edge remaining after the chamfering will be 2.9 mm. However, in the case of a glass plate having a thickness of 3 mm as shown in FIG. 9A, the height T of the edge of the glass remaining after the chamfering is 0.9 mm, and therefore, it is very difficult to perform the chamfering by putting the engaging stopper 52 of the chamfering width maintaining roller 50 by also putting the glass plate shape sensing roller.
Further, the greater the size of the glass plate and the thinner the thickness of the glass plate, the chamfering becomes more and more difficult. That is, if a glass plate is to be chamfered by mounting the glass plate a suction securing table, the chamfering width maintaining roller and the glass plate shape sensing roller are separately disposed below. Under this condition, the horizontally maintaining roller for horizontally maintaining the glass plate is also brought down by being separated from the glass plate, and therefore, the edges of the glass plate is lowered, with the result that the chamfering height is deviated from the set position.
Consequently, the lower edge of the glass plate is too much chamfered, while the upper edge of the glass plate is chamfered too little, thereby producing a defective chamfering.
Conventionally, a horizontally maintaining roller is used to support the side portion of the glass plate, so that the side finishing should be eased. However, if a chamfering is to be carried out after performing a side finish, or if a side finish is to be carried out after performing chamfering, the horizontally maintaining roller has to be detached and re-attached, with the result that the chamfering becomes very troublesome to carry out, as will as being time-consuming.